Flange corrosion phenomena affecting electrolysers are known to those skilled in the art. These phenomena take place especially in outer flange zones, in correspondence of gaskets. In such zones in fact, the stagnation of corrosive substances and the lack of oxygen needed for supporting passivation and hence for ensuring protection of the metallic material favour the onset of corrosion. To prevent these phenomena it is possible to rely on the activation of the flange by coating the same with a catalytic layer, for instance made of platinum or ruthenium oxide. This procedure is nevertheless complicated since coating with a catalyst requires high temperature treatments which may bring about a deformation of the flange.
On the other hand, if the flange has already been attacked by corrosion, an intervention is required to prevent its punching and the consequent leakage of matter from the electrolyser.
The methods known in the art provide in this case the removal of the damaged part, which requires cleaning the zone affected by corrosion and subsequently welding new material in correspondence therewith. This procedure however presents serious limitations since the stagnation of corrosive substances and corrosion by-products —such as TiH— in the corrosion zone hampers the effectiveness of the subsequent weld. These substances must therefore be removed very carefully in order to obtain a locally effective weld, which entails lengthy operations often leading to non optimal results.
It has thus been evidenced the need of providing a new method of corrosion prevention and new repairing techniques of corroded parts characterised by being quick, cheap and straightforward.